Internet services returned to Yemen on Tuesday after air strikes by the Saudi-led coalition caused a four-day outage.

“Connectivity collapsed after a series of deadly air strikes. The incident severely limited independent media and human rights monitoring efforts,” according to NetBlocks, a cybersecurity watchdog.

A Saudi-led air raid hit a telecoms facility in Hodeidah on Thursday, which is believed to be the cause of the nationwide internet outage.

At least three children playing nearby were killed, according to AFP.

On the same day, the coalition also bombed a prison in Saada controlled by Houthi rebels, leaving 91 people dead and more than 100 wounded, though the coalition denied it also targeted the prison.

The internet outage and the prison bombing put pressure on rescue and healthcare services in Saada, which were reportedly overwhelmed by the bombing’s aftermath.

The strikes followed drone-and-missile attacks by Yemen’s Houthi rebels on Abu Dhabi the previous week.

The United Arab Emirates, part of the Saudi-led coalition fighting the Houthis in Yemen, intercepted two more rebel missiles on Monday.

Yemen’s conflict has been raging since early 2015 and the recent flares in attacks mark the highest spike in military exchange in recent years.